Tape is a widely used medium for storing data. Tape cartridges are a popular format for storing data on tape, as they are usually smaller and less expensive than reel-to-reel tapes and the cartridge shell provides suitable protection for the tape media. Tape cartridges may be dual reel or single supply reel cartridges. A dual reel tape cartridge houses two reels and, in use, the tape is transferred from one reel to the other past a transducer, which may be a read device, a write device or a read/write device. A single supply reel cartridge has a single tape reel and, in use, the tape is transferred between the single supply reel and a take up reel that is an integral part of the data transfer apparatus.
Referring to FIG. 1, tape cartridges 10 are often loaded into data transfer apparatus by pushing the cartridge through an opening in the apparatus into a cartridge loading device. The cartridge loading device automatically moves the cartridge inwards and downwards to register on locating points and engage the tape reel(s) 12 with a drive member(s) 14 that engage(s) in a recess in the tape reel to transmit rotary motion to the tape reel. This process requires that the tape cartridge 10 must be clear of the drive member(s) 14 when it is loaded into the data transfer apparatus. Providing that clearance puts physical constraints on the sizing of the data transfer apparatus in the direction indicated by the arrow 16.
Data transfer apparatus for use with computers is typically designed to fit in a standard fixed-size bay. Historically, one of the most popular sizes (width) of tape used in tape cartridges for data transfer apparatus used in conjunction with computers has been approximately 4 mm. The demand for tapes with a greater storage area has led manufacturers to increase the length of the tapes used and, in more recent times, has led to an increased usage of wider tapes (for example 8 mm wide tapes). Since the height of a tape cartridge is at least slightly greater than that of the tape it houses, the use of wider tapes has presented designers with the problem of trying to fit larger cartridges into the same size of apparatus, or at least data transfer apparatus that will fit into a standard size bay.